FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a protein containing N-terminal ankyrin repeats which function in protein-protein interactions. Mutations in this gene are associated with autosomal dominant thrombocytopenia-2. Pseudogenes of this gene are found on chromosome 7, 10, 13 and 16. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Dec 2011] PHENOTYPE: Mice homozygous for a gene trapped allele have enlarged kidneys and hearts, exhibit increased lean body mass and adiposity, develop extreme obesity associated with hyperphagia rather than reduced energy expenditure, and show insulin resistance and gigantism. [provided by MGI curators]